Nascent struggle to stem the flow
As sea levels rise, climatologists watching Chennai are expecting to see flooding, drought and water shortages. This is a city whose population is growing so fast that estimates have shot up from 4.6 million in the 2011 census to 10.7 million according to Statista, as of 2019. Meanwhile, rampant urbanisation and poor urban planning have seen the total area occupied by water bodies shrink from nearly 12.6 sq km in 1893 to about 3.2 sq km in 2017, according to a 2019 study by the department of geology at Chennai’s Anna University.
In June 2019, after three consecutive deficient monsoons, the city’s four main reservoirs ran dry. Amid uneven rainfall and the shrinking and pollution of water bodies and aquifers, Chennai now leans heavily on desalination plants and groundwater.
Meanwhile, flooding is intensifying. In December 2015, a downpour of 494 mm — the heaviest one-day rainfall in Chennai since 1901 — wreaked havoc in the city. November 2021 went down as the third-wettest November in the city’s recorded history.
“Population growth, drastic changes in land-use patterns, loss of green cover, and inundation due to sea-level rise all make the city exceedingly vulnerable to climate change,” says Palanivelu Kandasamy, professor of environmental sciences at the Centre for Environmental Studies at Anna University. “Climate change action must shift from mitigation to adaptive strategies, and the state must accelerate the pace of the efforts.” Coastal embankments must be constructed where necessary, Kandasamy adds. Instead, marshlands and wetlands are being filled in for construction.
The Pallikaranai marshland, the only urban wetland in Chennai city and one that acted as a sponge in times of flooding, has shrunk by about 90% over less than half a century. A dumping ground and developments on and around it have reduced its area from about 5,500 hectares in 1965 to about 600 hectares in 2013, according to a 2019 report by an amicus curiae, senior counsel PS Raman, appointed by the Madras high court. Last year, the court directed the state government to declare Pallikaranai a protected Ramsar wetland.
For now, the biggest immediate concerns are the increasingly intense storm surges on the cyclone-prone eastern coast, says SA Sannasiraj, professor of ocean engineering at the Indian Institute of Technology (IIT) - Madras. “In 2020, there were four major cyclones affecting India — Amphan, Nisarga, Nivar and Burevi,” Sannasiraj says.
Last August the Tamil Nadu government began formulating a Climate Change Mission aimed at focusing on sustainable agriculture, water resources, forest and biodiversity, strategic knowledge, enhanced energy efficiency and solar power. The plan is to carry out 199 projects in these sectors by 2030.